This project is investigating the strong evidence for genetic and stress factors in the etiology of high blood pressure by looking for evidence of a genetic mediation of the response to stress, by studying monozygotic and dizygotic college age male twins. The study involves testing the changes in blood pressure and hormones having to do with blood pressure to a standardized stress protocol. The protocol will test the response to hand grip, mental arithmetic, mirror drawing, cold water and relaxation induction. Those tests which show evidence of an inheritable nature will then be investigated in subjects with high blood pressure and their offspring. BIBLIOGRAPHIC REFERENCES: Grim, C.E., Weinberger, M.H., Anand, S.K. Familial, Dexamethasone Suppressible, Normokalemic Hyperaldosteronism. In Juvenile Hypertension, (eds.) M.I. New and L.S. Levine, Raven Press, New York, 1977, p. 109-122.